]Hi I installed Mint through windows 7 with no problem. So I am using the windows boot loader. I now want to extend linux partition but when I run fdisk -l it only show the whole hard drive as if there were no partitions but of course there are two because one is windows. Gparted says there is no partitions either

As you stated yourself you have installed Mint through Windows. I am dead sure that this means you have used mint4win.exe from inside the running Windows 7 and performed a mint4win installation of Mint 15.

In this case fdisk and gparted are right. Your harddisk does only hold the Windows partitions. On one of these partitions there will be a folder named \linuxmint.
Inside this folder \linuxmint there will be a subfolder named disks. Inside the subfolder \linuxmint\disks there will be two files: root.disk and swap.disk.

You can verify my words either from inside the running Windows 7 with the help of Windows Explorer.
Or you can verify my words from inside the running Mint 15 by launching Nemo and navigating to /host/linuxmint/disks.

root.disk is a container file. It holds the Linux Mint filesystem, very likely formatted as the filesystem ext4.
swap.disk is a container file, too. It holds the Linux Mint swap space.

In order to increase the size of the Mint filesystem, you will have to increase the size of the container file root.disk.
You can find the instruction on how to do so here: [url=http://ubuntuforums.org/showthread.php?t=1625371]HOWTO: Resize the WUBI virtual disk[/url].
The instruction has been written by one of the few people in the Linux forums who really know what they are talking about when they talk about Wubi installations, bcbc. He is involved in the Wubi development. And mint4win is just the Mint flavour of Wubi.

HTH,
Karl
--
P.S. from a mint4win installation of Mint 13 on a Windows 7 machine:

As you wish to increase the size of your Mint filesystem and as according to your own words you installed Mint through Windows, i.e. you performed a mint4win installation, therefore I wonder whether you might also be affected by the problem reported here: [url=http://forums.linuxmint.com/viewtopic.php?f=46&t=131139]mint4win usable drive space and disk image size mismatch[/url]?

Essence:
A user had only performed the Windows part of any mint4win installation.
Having completed the Windows part he had incorrectly assumed the Mint installation had been completed.
The truth is, the actual Mint installation is part 2 of the mint4win installation. It has to be initiated manually after the reboot by clicking on the "Install Linux Mint" icon on the desktop.
As the user had failed to do so he kept on using the Mint live system (now located on the harddisk), which limited the disk space available inside Mint to a minimum.
The solution was achieved by completing the missing installation step.

Karl

Old bugs good, new bugs bad! Updates are evil: might fix old bugs and introduce no new ones.